Explosionproof seal for floating roofs



Nov. 24, 1942. J. H. WIGGINS EXPLOSION PROOF SEAL FOR FLOATING ROOFS Filed Aug. 26, 1940 5 Sheets-Sheet 1 FIG].

- I INVENTOR; (JOHN H. W/GGINS 'HTTORNEY Nov. 24, 1942. J. H. WIGGINS2,302,904

EXPLOSION PROOF SEAL FOR'FLOA'IING ROOFS Filed Aug. 26, 1940 sSheets-Sheet 2 INVENTOB .r/OHN H. WIGGINS av ficawf W ATTORNEY Nov. 24',1942.' J. H. WIGGINS EXPLOSION PROOF SEAL FOR FLOATING ROOFS Filed Aug.25, 1940 S SheetS-Sheet 5 I0 J7 low v 7 #6 7 I0 29.

INVENTOR; JOHN H. WIGGINS 6r Wuwv hr? WM :4 TTORNE Y Patented Nov. 24,1942 UNITED STATES PATENT OFFICE EXPLOSIONPROOF SEAL FOR FLOATING ROOFS'7 Claims.

This invention relates to floating roof seals of the type that comprisean annular shoe or equivalent element arranged so as to engage thevertical side wall of the tank, and a closure, commonly referred to as aprimary seal, for the gas space between saidshoeand the peripheral edgeportion of the floating roof.

One object of my invention is to'provide a floating roof seal, which, inaddition to'having the desirable features and distinguishingcharacteristics of conventional seals now'in general use, is soconstructed that in the event of an explosion in the gas space at theperipheral edge of the roof, the primary seal will automatically assumea position to produce a vent opening of variable size and sufiicientarea to quickly relieve the pressure produced by the explosion, andthereafter will automatically resume its normal position and make saidgas space gas-tight.

Another object is to provide a floating roof seal in which the primaryseal and side wall shoe are maintained in gas-tight relationship in anovel manner that simplifies the construction and improves the operationof seals of the general type or kind referred to.

Another object is to provide a floating roof seal in which the meansemployed to force the shoe outwardly towards the tank side wall is alsoutilized to maintain a tight joint between said shoe and the primaryseal.

Another object is to provide a floating roof seal, in which the sidewall shoe and the primary seal are combined in gas-tight relationship insucha way that said elements can slide and move relatively to each otherwithout destroying the gas-tight joint or connection betweensaid-elements.

Another object is to provide a floating roof seal, in which the primaryseal and side wall shoe are combined in a novel manner that permits theprimary seal to increase and decrease circumferentially as the shoeincreases and decreases circumferentially, without disturbing thegas-tight joint or connection between said primary seal and shoe.

Another object is to provide a split, ringshaped side wall shoe that isprovided with a novel means for producing a slidable, gas-tight jointbetween the ends of said shoe.

Another object of my invention is to provide a floating roof seal, inwhich the side wall shoe has circumferentially sliding lapped portions,and the primary seal has a continuous connection with said lappedportions.

And still another object of my invention is to provide a floating roofseal, whose co-acting parts that are in sliding engagement with eachother and with the tank side Wall, are constructed in the form ofcontinuous expansible and contractible rings, free from gaps or openspaces that are difiicult to maintain in a gas-tight condition. Otherobjects and desirable features of my invention will be hereinafterpointed out.

My improved seal is similar in general design to a type of floating roofseal that is now in general use, in that it comprises acircumferentially flexible, annular-shaped, split shoe disposedvertically in parallel, or approximately parallel, relationship with theside wall of the tank, a means for mounting said shoe on the floatingroof in such a way that said shoe can move relatively to the roof andadapt itself to the tank side wall, a means for exerting outwardpressure on said shoe in a direction tending to press it against thetank side wall, and a primary seal, preferably formed of gas-tight,fire-resistant fabric, arranged between said side wall shoe and theperipheral edge of the roof and combined with said elements in agas-tight manner. It is distinguished from prior floating roof seals,however, in that the inner andouter edges of said seal are not directlyattached or fastened to the floating roof and to the sidewall shoe,respectively. Instead, one edge of said primary seal is secured,attached or fastened to one of the parts with which it co-acts and theopposite edge of said seal is held in yielding engagement with theotherpart with which the seal co-acts. Accordingly, in the event of anexplosion in the gas 7 space at the edge of the floating roof, oneentire edge'of the primary seal is capable of separating or moving awayfrom one of the parts with which it co-acts, thereby producing a ventopening of variable size, that is of ample area to quickly relieve thepressure produced by or resulting from the explosion. This highlydesirable result can be attained in various ways, and while I prefer tofasten or attach the inner edge of the primary seal to the floating roofand maintain the outer edge of said seal in sliding, yielding engagementwith the side wall shoe by spring pressural wish it to be understoodthat my invention is not limited to the particular structure hereinillustrated. In addition to providing a quick-acting venting devicehaving a variable outlet of ample size to afford instant relief for thegas space, the structure herein illustrated and described is highlydesirable, in that it allows the primary sealto slide relatively to theside wail'shoe and permits said seal to increase and decreasecircumferentially.

Still another advantage of my invention is that it greatly simplifiesthe operation of cornbining a fabric primary seal with a side wall shoe.While my broad idea contemplates the use of any suitable means forholding the primary seal in gas-tight relationship with the side wallshoe, I prefer to build the structure so that the means which isemployed to force the shoe outwardly towards the tank side wall, is alsoutilized to yieldingly hold the primary seal in engagement with the sidewall shoe. This reduces the cost and simplifies the installation of thestructure and it locates the metal parts subject to corrosion on theexterior of the gas space.

The side wall shoe, instead of being provided with a split or gap sealedby fabric attached to the end portions of the shoe, is constructed in73118 form of a split ring provided with overlapped i or overlapping endportions that are machined or planed throughout the height of the shoe,so as to produce co-acting, sliding, metallic surfaces that remain ingas-tight engagement with each other when the shoe expands andcontracts.

In addition to providing an efiicient expansion joint in the shoe, thistype of construction makes it possible to produce and maintain acontinuous gas-tight joint or connection between the primary seal andthe side wall shoe.

Figure 1 of the drawings is a vertical, fragmentary sectional viewthrough the tank side wall and shoe, illustrating the means employed toexert outward pressure on the shoe and also to hold the primary seal ingas-tight engagement with the shoe, and also showing how the auxiliaryseal is mounted on the shoe.

Figure 2 is an elevational view of the parts shown in Figure 1, lookingoutwardly from the center of the tank.

Figure 3 is a vertical, fragmentary sectional view, through the tankside wall and shoe, illustrating the swinging hangers on the floatingroof from which the side wall shoe is suspended.

Figure 4 is an elevational view of the parts Figure 7 is a sideelevational view of the parts shown in Figure 6; and

Figure 8 is a plan view, more or less diagrammatic, for the purpose ofshowing the sliding overlapped end portions of the shoe that provide forthe expansion and contraction of the shoe.

In the accompanying drawings, which illustrate the preferred form of myinvention, A designates the circuit, vertically-disposed side wall of aliquid storage tank, and B designates a floating roof in said tank. Theannular space between said tank side wall and the peripheral edge of theroof is sealed by a structure commonly referred to as a floating roofseal, that comprises a circumferentially flexible annular side wall shoeI, which is adapted to bear against the inner face of the tank side wallA, a primary seal 2, usually constructed from gas-tight, fireresistantfabric, disposed between the shoe I and the roof B and combined withsaid parts in a gas-tight manner, and an auxiliary seal or secondaryseal 3, usually constructed of fabric, mounted on the upper edge portionof the shoe I and arranged so as to normally bear snugly against theinner face of the tank side wall. The shoe I may be mounted in anypreferred or suitable way on the roof B, and is herein illustrated asbeing adjustably suspended by links 4 from swinging hangers 5 on theroof. Similarly, any preferred or suitable means may be used to mountthe secondary seal on the upper edge portion of the shoe I. In the formof my invention herein shown, the fabric constituting the secondary seal3 has its bottom edge clamped to the shoe I by clamping rod or ring 6,and the top edge of said fabric is positioned in and gripped tightly bycarriers 1 carried by rock arms 8 mounted in bearings 9 attached to theinner side of the shoe I at the upper edge of same. Preferably, two rockarms are provided for each of the carriers I, and each carrier isassociated with a spring arm I0 mounted on the shoe I and arranged so asto force the carrier outwardly, thereby causing the secondary seal 3 tobe held pressed tightly against the inner face of the tank side wall. Asshown in Figure 5, the carriers I are arranged end to end around theentire circumference of the shoe, and the secondary seal 3 isconstructed in the form of a continuous ring that is cable of stretchingand contracting sufficiently to accommodate itself not only to changesin the shape of the tank side wall, but also to variations in thecircumferential length of said wall, which, in welded tanks, oftenranges from one inch to three inches.

The fabric constituting the primary seal 2 has its inner edge or bottomedge secured in any suitable way in a gas-tight manner to the peripheralportion of the floating roof B. I have herein shown said fabric as beingclamped to the roof by a clamping ring or rod II held in place by wedgesI2 positioned in lugs I3 attached to a laterally-projecting portion ofthe roof that overhangs the annular gas space between the peripheraledge of the roof and the side wall shoe I, as shown in Figure 3. Aspreviously stated, it has heretofore been the universal custom to boltor otherwise securely fasten the primary seal to the side wall shoe. Ihave departed radically from said practice by combining the primary sealand side wall shoe in such a way that they are held yieldingly inengagement with each other, and are capable of sliding relatively toeach other, both vertically and horizontally, or circumferentially,without destroying or disturbing the gas-tight joint or connectionbetween said elements. As previously explained, one advance of such aconstruction is that if an explosion occurs in the gas space, the entireprimary seal 2 will separate from the side wall shoe I, and will open aswide as necessary to relieve the pressure produced by the explosion, andthereafter will immediately snap shut or resume its normal position.Another advantage is that if the shoe I moves sideways relatively to theroof, the primary seal 2 will remain at rest or stationary relatively tothe roof, or, in other words, will not move sideways with the shoe. Thisis of particular advantage with a tank side wall that is badly out ofround.

I attain the desirable results just referred to by employing a pluralityof spring-pressed arms I4 to fold or press the upper edge of the primaryseal 2 against the inner side of the shoe I. Said arms M are pivotallymounted, or rockably mounted on the roof B at or adjacent the peripheraledge of said roof, and preferably the upper ends of said arms areattached to clips or carriers l5 which are securely fastened to the topedge of the primary seal 2, thus causing the primary seal to besuspended from rockable devices on the roof disposed so as to force theprimary seal outwardly against the side wall shoe. In the form of myinvention herein illustrated the top edge portion of the fabricconstituting the primary seal 2, is folded over and positioned inside ofU-shaped clips or carriers l5 that tightly grip said fabric. arrangedend to end around the entire circumference of the primary seal, and eachclip is combined with one or more spring-pressed arms 14. Preferably,and as shown in Figure 4, two

springs arms M are provided for each of the U- shaped members or clipsattached to the top edge of the primary seal. The arms M are hereinshown as being rockably mounted in the roof lugs l3, previouslydescribed, and each pair of arms It has associated with same a spring I6that exerts an outward thrust on a cross bar l'! which bears against thearms, as shown in Figure l. One convenient and inexpensive way offastening the upper ends of the spring-actuated arms M to the carriersor clips I5, is to provide each of said arms at its extreme upper endwith a disk-shaped portion l3 that is embraced by bendable lugs or earsit on the carrier I5, as shown in Figure 2. In floating roof seals ofconventional design springs or spring-actuated devices are commonlyemployed to force the shoe outwardly towards the side wall of the tank.In my improved seal the spring-pressed arms 14 perform the dual functionof forcing the shoe I outwardly towards the side wall A of the tank, andalso holding the upper edge portion of the primary seal 2 in gas-tightengagement with said shoe. In addition to being inexpensive and easy toassemble, the construction above described is desirable, in that thearms 14, the supporting means, and actuating springs for same, and thedevices used to connect saidarms to the primary seal are all located onthe exterior of the gas space at the edge of the roof.

The shoe l is made up of relatively long metal plates joined together byrivets 20, as shown in Figure 5, and said shoe is constructed in theform of a split ring having overlapped or overlapping end portions thatare maintained in gas-tight sliding engagement with each other, as shownin Figure 8. Preferably, said overlapping portions are formed by tworelatively heavy, smooth-surfaced plates 2! and 22. The plate 22, whichis attached to one end of the shoe, extends throughout the entire heightof the shoe, and projects laterally beyond the end of same, as shown inFigure 6, the inner side of said plate being machined or planed so as toproduce a smooth fiat surface. The co-acting, smooth-surfaced plate 25.is attached to the opposite end portion of the shoe, and is arranged inoverlapping relationship with the plate 2!, so as to produce a gas-tightsliding joint between the ends of the shoe that provides for theexpansion and contraction of the shoe. Any suitable means may be used tohold the overlapping plates 2i and 22 in gas-tight relationship, but Iprefer to attach a plurality of horizontally-disposed bars 23 to theplate 2| in spaced relationship with the inner side of same, and weld avertically-disposed, round rod Said clips are :24 to said: bars, so. asto produce a guiding memher that bears against the inner side of the,plate 22 and holds it in gas-tight, sliding relationship with the plate2 I. Said rod or guiding member 24 is preferably adjustably connected tothe plate 2i and in the structure herein shown, the adjustment of saidmember24 is obtained by bolts 25 that pass through the bars 23. Theterminal end of the inner surface of the plate 22 is beveled, as shownin'Figure 6, so as to facilitate introducing said plate into operativeposition between the plate 2i and the overlapping. vertical rod 24,

and if desired, cement or other suitable plastic material 28 can bearranged in the angles formed by the ends of the shoe and the plates 2|and 22, as shown in Figure 6, so as to eliminate sharp corners or angleson the inner side of the shoe I, and produce a substantially continuoussurface for 'theprimary seal 2 to slide on.

In installing the seal above described, the shoe i is lowered intooperative position between the floating roof B and the side wall A ofthe tank, and after it has been pressed firmly against the tank sidewall, the plates 2i and 22 are bolted to the end portions of the shoe.The shoe isv then mounted on the hangers 5, and set at the proper levelby adjusting the links 4 which suspend the shoe from the hangers, andthereafter the lugs 53 are welded to the top surface of the roof. Thenext step of the installation is to fasten the U- shaped metal clips iiito the top edge portion of the primary seal 2, after which the upperends of the rock arms M are fastened to said clips by bending the earsor lugs [9 over the disk-shaped portions i8 011 the said arms. The armsIt can now be set in slots provided for same in the lugs iii, andcombined with the cross bars H and springs l6 that are used to force theshoe I outwardly and hold the primary seal in gas-tight engagement withsaid shoe. After the angles between the ends of the shoe and theattached plates 2| and 22 have been filled with cement 26, as previouslyexplained, the nuts on the bolts 25 of the bars 23 are tightened so asto produce suincient pressure between the plates 2| and 22 to maintain agas-tight joint between the same, but still permit said plates to slideon each other when the shoe expands and contracts, due to variations inthe shape and circumferential length of the tank side Wall.Subsequently, the bottom edge of the primary seal is fastened in agas-tight manner to the floating roof, and the secondary seal 3 ismounted on the upper edge portion of the shoe i in such a way as toproduce a continuous tank side wall contacting element that stretchesand contracts sufficiently to accommodate itself to changes in the shapeand in the circumferential length of the tank side wall.

Having thus described m invention, what I claim as new and desire tosecure by Letters Patent is:

l. The combination of a floating tank roof, an annular shoe surroundingsaid roof and adapted to engage the side Wall of the tank in which theroof is positioned, a primary fabric seal for the gas space, having itsinner edge attached to the roof and its outer edge arranged in sliding,yielding engagement with said shoe, means carried by the roof for sosupporting the outer edge of the primary seal, and separate and distinctmeans also carried by the roof for supporting the shoe.

2. A structure of the kind described in claim 1, in which the supportingmeans for the shoe and for the seal are located on the exterior of thegas space.

3. The combination of a floating tank roof, an annular shoe surroundingsaid roof and arranged vertically in sliding engagement with the sidewall of the tank in which the roof is positioned, said shoe having asubstantially continuous surface at the inner side of same, swinginghangers on the roof, means for suspending the shoe from said hangers, aprimary seal having its inner edge fastened or attached to said roof,spring-actuated devices on the top side of the roof that support theouter edge of the primary seal and force it outwardly into tightengagement with the inner side of the shoe, and a, spring-pressedsecondary seal mounted on said shoe adjacent the top edge of same forprotecting the joint between said shoe and the tank side wall.

4. In a floating roof seal, the combination of a floating roof, anannular side wall shoe carried by the roof and arranged with its lowerend spaced away from the peripheral edge of the roof, a closure for thegas space between said shoe and roof, formed from a substantiallyannular-shaped, flexible element extending unbrokenly around the entirecircumference of the gas space, said closure element having one of itsedge portions attached by a gas-tight joint to one of said parts andhaving its free edge portion, arranged in horizontal, sliding contactwith said other parts, and means for normally maintaining said closureelement in yielding, sliding engagement with the part with which thefree edge portion of said closure element is in horizontal, slidingcontact.

5. A floating roof seal of the kind described in claim 4, in which thepart contacted by the free edge portion of said closure element has asubstantially continuous surface engaged by the free edge portion ofsaid closure element and arranged so as to be capable of movinghorizontally relatively to same.

6. In a floating roof seal, the combination of a side Wall shoe, afloating roof, a seal for closing the gas space between said shoe androof, said seal having its inner edge portion attached or fastened tothe roof and having its outer edge portion arranged in yielding, slidingengagement with the shoe, means on the roof for supporting the shoe, andan independent means for supporting the outer edge portion of said sealand normally maintaining the same in separable relationship with saidshoe.

'7. A floating tank roof seal of the kind described in claim 6, in whichthe means that supports the outer edge portion of the seal for the gasspace, presses said seal against the shoe and also forces the shoeoutwardly toward the tank side Wall with which said shoe co-acts.

JOHN H. WIGGINS.

